Non-SFI mode: Use dummy PID for NaCl's IPC channel on Linux platform.

ipc/ipc_channel.h

Index: ipc/ipc_channel.h
diff --git a/ipc/ipc_channel.h b/ipc/ipc_channel.h
index 2fc52cb58750684ffc4aa40e3ff3565c69908675..e8d7eac7325a5ea54b2e73ec29cb0f590a0bc7ac 100644
--- a/ipc/ipc_channel.h
+++ b/ipc/ipc_channel.h
@@ -211,7 +211,7 @@ class IPC_EXPORT Channel : public Sender {
   static std::string GenerateVerifiedChannelID(const std::string& prefix);
 #endif
 
-#if defined(OS_LINUX)
+#if defined(OS_LINUX) || defined(OS_NACL_NONSFI)
   // Sandboxed processes live in a PID namespace, so when sending the IPC hello
   // message from client to server we need to send the PID from the global
   // PID namespace.